HPA2: Hpa2 is a member of the Gcn5-related N-acetyltransferase (GNAT) superfamily, a family of enzymes with diverse substrates including histones, other proteins, arylalkylamines and aminoglycosides.As a GNAT superfamily member, this yeast protein was tested in vitro and found to acetylate histones H3 and H4, with a preference for lysine-14 of H3. Hpa2 has a high degree of homology with another yeast GNAT protein, Hpa3, which displayed very poor HAT activity in in vitro assays but did autoacetylate. (1)